Lateral Foam Tubes Configurations...

[Eno821302]

Hey folks;


I'm on the job with one of the new oil facilities emerging in the North. We're fortunate enough to have access to LFTs on all of our storage tanks. For those of you who may call them something else, basically I'm talking about a piping system accessible from outside the berm that leads to "foam boxes" that deliver foam solution straight into a tank from the top. We pump water and foam up in required percentages, and the foam boxes do the rest.

Currently our setup involves up to 12x2.5 / 3" connections. Each tube is finished by a siamese. The setup is daunting and impractical... we're looking for modifications. We've got a few ideas- but we're looking for an "outside the box" opinion.

Anyone else currently have these systems available on their tanks? Can they be expected to work? Will they be damaged early in a fire?


Thanks!

[robertr2m]

I have worked in a terminal in the past with a similiar setup. The tank in question was a fixed roof tank and contained Propylene Oxide.

The tank was being filled from a barge that used high pressure N2 to push the product into the tank when it was supposed to use low pressure. The tank over pressured and the chime of the tank breached causing a vapor release and fire.

The LFT's where damaged during the explosion and where unusuable (6 I think where installed). In addition, the connections where located at the bottom of the tank and where not approachable.

Large diameter foam cannons lobbed foam into the effected tank and master streams where applied to exposed tanks within the dike area.

When the tank was rebuilt, the LFT's where replaced with the connections outside the dike wall (as well as the other tanks where modified to extend the connectiopns outside the wall).

Monitors where also installed on the top tank decks so water/foam could be applied from a nearby tank at the same height. These connections where also moved outside the dike wall. 550 totes of AFFF where staged nearby the connections and are on a PM schedule. Height and diameter of standpipe to the monitors was stenciled near the connection to assist pumper in calculating.

Haven't had another incident so can't tell you if the measures taken assisted or improved protection or suppression.

When involved with suppression a floating roof tank at a fuel depot, the roof sunk and a fire resulted. It was some type of fuel oil. The top of the tank and LFT's had already been damaged by the fire before suppression could be started. What measures the company took after is not known as we responded as mutual aid.

Hope this helps... be safe.

R2

[jtstoney]

Eno,

These systems in the US are called foam chambers, and each one should be engineered for the particular hazard.

Each chamber can be feed individually, or by a ring manifold.

The piping can be tied to a system, or extended out to a FDC.

The FDC should be labeled with PSI and GPM required.

If not, your shooting in the dark.

Drop me a line if you need help on this.

JT

[Eno305]

Hey JTS...

We do have these systems integrated in our tanks already, and the engineers have undertaken the responsibility of tagging each tube so we know what we need...

Question for you!

Is it plausible to adapt the foam chambers (as you call them) to either supply the chamber OR a hose line? The reason I ask is that it sounded like from other fire incidents that I have heard of that tanks have been used to position elevated master streams. Logistically, it'd be a lot easier for us to just tie into the system a la standpipe than it would be to try and dork around with that amount of hose. Do you know if this has been done before?

[jtstoney]

Eno,

Sorry its taken so long for a reply. I got knocked out of the system and couldn't post.

In response to your suggestion, yes, it could be done as you suggested, but its not acceptable practice to include other discharge devices on a fixed flow system.

The reason is, the system is designed for a constant flow, and any devices added at the scene are of unknown flow, and will change the application rate of the fixed system devices. Each foam chamber has a specific orfice, based on the pressure and flow needed calculated on the tank diameter and fuel type

In other words, the designers of the system don't know if you are going to add a 250 gpm handline or 3ea 500 gpm monitors. Each of those would effect the volume to the chambers and require an orfice change.

You probably need to leave the FDC connections to the chambers on a seperate dedicated system, and find a different supply for portable applications.

Most facilites add fixed monitors around the tank for just the reason you mentioned. These monitors can be fitted with Self Educting nozzles for foam use, or the nozzle can be removed, and an eductor and hose can be attached for mobile handline operations.

JT